1. Field
The present disclosure relates generally to composite materials and, in particular, to manufacturing composite structures. Still more particularly, the present disclosure relates to a method and apparatus for forming shapes in composite structures.
2. Background
Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Composite materials may be used in aircraft to decrease the weight of the aircraft. This decreased weight improves performance features such as payload capacities and fuel efficiencies. Further, composite materials provide longer service life for various components in an aircraft.
Composite materials are strong, light-weight materials created by combining two or more functional components. For example, a composite material may include reinforcing fibers bound in a polymer resin matrix. The fibers may be unidirectional or may take the form of a woven cloth or fabric. The fibers and resins are arranged and cured to form a composite material.
Further, using composite materials to create aerospace composite structures potentially allows for portions of an aircraft to be manufactured in larger pieces or sections. For example, a fuselage in an aircraft may be created in cylindrical sections. Other examples include, without limitation, wing sections joined to form a wing or stabilizer sections joined to form a stabilizer.
In manufacturing composite structures, layers of composite material are typically laid up on a tool. The layers of composite material may be comprised of fibers in sheets. These sheets may take the form of fabrics, tape, tows, or other suitable forms. In some cases, resin may be infused or pre-impregnated into the sheets. These types of sheets are commonly referred to as prepreg.
The different layers of prepreg may be laid up in different orientations and different numbers of layers may be used depending on the thickness of the composite structure being manufactured. These layers of prepreg may be laid up by hand or by using automated lamination equipment such as a tape laminating machine or a fiber placement system.
Oftentimes, tooling devices are used to form surfaces of the composite structure. For instance, a tooling plate may be placed over the layers of composite material to aid in forming a composite part with a desired shape.
The tooling plate is typically placed on the composite part prior to curing. A protective coating may be placed between the composite part and the tooling plate. During curing, the tooling plate transmits pressure, heat, or both pressure and heat to the composite layup. As a result, the tooling plate creates a smooth surface for the composite part.
Tooling plates have various shapes and sizes and are formed from a number of different types of materials. The size and shape of a tooling plate is selected based on the desired shape of the surface of the composite part for which it is used.
After forming the shape of the tooling plate, operations may be performed on the tooling plate to create various features on the tooling plate. These features may include alignment features used to position the tooling plate with respect to the tool used for forming the composite part. For instance, holes may be drilled in the tooling plate to create an alignment feature.
Manufacturing tooling plates in this manner, however, may take more time than desired, increase the risk of error in performing operations on the tooling plate more than desired, or both. For instance, when the tooling plate is made of composite material, operations may be performed on the tooling plate after curing. Performing these operations on the tooling plate after curing may cause undesired inconsistencies to occur in the tooling plate. Examples of inconsistencies include voids, delamination, foreign object debris (FOD), cracks, and other types of inconsistencies. If a composite part is formed from a tooling plate with inconsistencies, that composite part may not have a shape or surface properties that are desired. As a result, the composite part may need to be reworked or discarded.
Moreover, a tooling plate may be used to form a number of composite parts over the lifetime of the tooling plate. After being used for a period of time, the tooling plate may become worn and the alignment features may deform. As a result, the alignment features may not provide a desired level of alignment for the tooling plate when manufacturing composite parts. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.